Process and apparatus for injecting fluid into a well



Dec. 6, 1966 WY B. BELKNAP PROCESS AND APPARATUS FOR INJECTING FLUIDINTO A WELL Filed March 9, 1964 INVENTOR.

W. B BELKNAP ,4 T TORNEYS United States Patent 3,289,763 PROCESS ANDAPPARATUS FOR INJECTING FLUID INTO A WELL William B. Belknap,Bartlesville, Okla, assignor to Phillips Petroleum Company, acorporation of Delaware Filed Mar. 9, 1964, Ser. No. 350,254 13 Claims.(Cl. 166-40) This invention relates to a process and apparatus forinjecting a fluid into a well thru a tubing string having a pump on thelower end without removing the pump from the well.

The production of oil from subterranean oil-bearing strata thruproduction wells having a tubing string and a pump on the lower endthereof frequently requires in jection of fluid into the well. Anillustration of this situation is in the injection of steam into an oilwell to heat the oil-bearing stratum to increase oil production or flowof oil into the well. In one technique of operation, superheated steamis injected into the well and after an extended heating period withsteam, the oil flowing into the well is produced by conventional pumpingmeans. The injection of steam is then renewed to cause more oil to flowinto the Well and after an extended heating period, the oil in the wellis again pumped to the surface. In this alternating heating andproduction technique, it has been considered necessary to pull the pumpout of the well in order to inject steam into the stratum. In someapplications of this method it has even been necessary to pull thetubing string for the steam injection phase of the operation.

This invention is concerned with a method and means of injecting a fluidinto an oil-bearing stratum thru a tubing string having a pump on thelower end without pulling the pump from the well.

Accordingly, it is an object of the invention to provide a process andapparatus for alternately injecting steam or other heating fluid into anoil-bearing stratum thru a tubing string in a well having a pump in thelower end of the tubing string, to heat and cause oil to flow into thewell and thereafter pumping the oil from the well without withdrawingthe pump and rods from the well. Another object is to provide a simplemethod and a paratus for injecting a fluid into a production well havinga pump in the lower end of a tubing string therein with out puliing thepump from the well. Other objects of the invention will become apparentto one skilled in the art upon consideration of the accompanyingdisclosure.

A broad aspect of the invention comprises providing an expanded sectionof tubing in the tubing string just above the pump on the lower end ofthe string, said section being of greater length and internal diameterthan the length and external diameter of the pump or pump plunger sothat a passageway is formed around the pump or plunger when retractedinto the expanded section, retracting the pump into the expanded sectionwhen injection of fluid is desired, and injecting fluid thru the tubingint-o the bottom of the well and into the surrounding stratum. Inapplications of the invention in which a tubing type pump is utilized,the working barrel of the pump is attached to the lower end of thetubing and the plunger is suspended on the llower end of the sucker rodand it is necessary to utilize a pump of this type which includes astanding valve retractable with the plunger. Pumps of this type areconventional and available from various manufactures. In anotherapplication of the invention, a rod pump or insert pump is utilized inwhich the complete unit, both the plunger and the working barrel, islowered into a well on the lower end of the sucker rod and the completeunit is retractable into the expanded section so as to permitunobstructed flow of injected fluid thru the tubing string around thepump and into the bottom of the Well. With either type of pump, all thatis necessary is to lift the sucker rod sufliciently to position the pumpor pump plunger within the expanded joint or section of tubing so as toprovide a fluid flow path around the pump or plunger and then inject thesteam or other heating fluid thru the tubing string for any suitableheating period.

Superheated steam at a temperature in the range of 300 to 750 F. is thepreferred heating medium. However, hot water, hot hydrocarbons (normallyliquid or normally gaseous), hot gases, such as air, flue gas, 0 ornitrogen, as well as other gaseous and liquid media may be injected inaccordance with the invention. In the ensuing discussion of theinvention, steam will be the injected heating medium.

When injecting steam at a temperature in the range of 300 to 750 F. and,particularly, at 550 F. there is a substantial expansion of the tubingstring up to 15 or more, depending upon the depth of the producing zonewhich determines the length of the tubing string. In one application ofthe steam injection and pumping process the expansion of the tubingstring amounts to approximately 12'. This means that provision must bemade for slippage of the tubing string thru the packer used to pack offthe casing-tubing annulus just above the expanded section of tubing.Packing; off this annulus is practiced in order to decrease the loss ofheat to the surrounding overburden and problems which would occur withresulting expansion of the casing.

A more complete understanding of the invention may be had by referenceto the accompanying schematic drawing of which FIGURE 1 is an elevationin partial section showing a preferred arrangement of the apparatus ofthe invention; FIGURE 2 is a horizontal section taken on the line 2-2 ofFIGURE 1; and FIGURE 3 is an elevation in partial section of apparatussimilar to FIGURE 1 utilizing another type of pump.

Referring to FIGURE 1, an oil-bearing stratum 10 is penetrated by a well12 which is provided with a case 14 extending approximately to the topof the stratum from a well head 16. A tubing string 18 extends thru thewell head and thru stratum 10. A pump 20 comprising a working barrel 22and a plunger 24 is positioned on the lower end of tubing string 18, theplunger 24 being attached to sucker rod string 26. The standing valve 28of the pump is seated on seat 30 so as to form a seal therewith and isretractable with plunger 24 when it is desired to retract the plunger ashereinafter described. Pump 20 is a conventional tubing pump availablefrom different manufacturers. It must be of the type in which thestanding valve is retractable with the plunger and detachably connectedthereto by a threaded or .l-lock joint.

An enlarged or expanded section or joint of tubing 32 is provided aboveand close to pump 20 so that plunger 24 with standing valve 28 may beattached thereto and may be withdrawn or retracted to the positionillustrated by dotted lines within section 32. In the retracted positionthe annulus 36 between pump plunger 24 and tubing section 32 provides apassageway for fluids injected thru the tubing string into the bottom ofthe well and into stratum 10.

Packer 38 is preferably set just above tubing section 32 and is a typeavailable commercially which allows substantial movement of tubing 18vertically thru the packer. In one embodiment, =this packer is about 22long and provides about 15' of slippage of tubing 18 while stillmaintaining the desired seal between the packer and the tubing. In thesame embodiment of the invention pump 20 has a 12' stroke utilizing aplunger 2%" OD. operating in a 3" LD. tubing string and tubing type pumpbarrel. Tubing section 32 has a 4' ID. so that annulus 36 is therebyproviding adequate flow path for injected fluids around pump 20 whenretracted to the injection position in conduit 32. Tubing section 32 ispositioned close to pump 20 and connected thereto by a short section ofstandard 3" tubing 40 so as to minirmize the required distance formoving pump 20 into tubing section 32. This makes it feasible to retractthe pump or pump plunger with the pumping unit at the well head withoutthe use of a conventional pulling unit.

It is also within the scope of the invention to position tubing section32 above packer 38' as shown in dotted lines in this position. In such acase packer 38 would be located just above pump 20.

In unconsolidated strata, a perforated linear 42 is positioned in thebottom of the well within stratum to minimize sand influx into the wellwith the produced oil. In some oil-bearing formations such asunconsolidated sands the perforated linear 42 is packed with a coursegravel to further minimize sand production.

Referring to FIGURE 2, pump or pump barrel 24 is shown in retractedposition within expanded tubing section 32 providing annulus 36 betweenthe inner wall of the tubing section and the outer wall of the pump.Sucker rod 26 connects with the top of the pump.

In FIGURE 3, corresponding elements to those in FIGURE 1 arecorrespondingly numbered. A rod type pump 50 comprises working barrel52, travel-ing barrel 54, traveling valve 56 in the lower end oftraveling barrel 54, and standing valve 58 in the bottom of workingbarrel 52. A seat and hold down 60 in the bottom of the pump and tubingsection 62 cooperate to seal the bottom end of tubing section 62 andhold the working barrel of the pump in the bottom thereof. Positioningof traveling valve 56 in the lower section of traveling barrel '54. ispre ferred when the well produces any appreciable amount of gas, sincethis type of pump is more resistant to gas lock.

Pump '50 is readily retractable from pumping position into tubingsection 32 by applying pulling force on sucker rod string 26 and liftingthe pump into the retractable position illustrated in dotted lineswithin section 32.

Either the pump plunger illustrated in FIGURE 1 or the rod pumpillustrated in FIGURE 3 is easily retractable into the expanded tubingsection to permit injection of fluid into the producing well in which itis positioned. In operating in accordance with the invention, steam,preferably at an elevated temperature in the range of 300 to 750 F. isinjected thru the tubing string with the pump in retracted position andthe steam injection is continued until a substantial amount of oil hasbeen caused to flow int-o the well by the heating produced by the steam.Obviously, heat applied to the producing formation renders the oiltherein less viscous and more readily flowable so that a substantialamount of the more fluid oil flows into the well. After this hasoccurred, the steam injection is terminated and the pump is lowered intopumping position so that pumping can take place to remove the oil fromthe well. After the flow of oil into the well has become insuflicient towarrant further pumping, the pump plunger or pump pre se is againretracted to the desired position in the expanded section of the tubingstring and injection of steam is resumed. This alternate steaming andproduction is continued until the process is no longer economicallyfeasible.

The invention is applicable to the production of oil from various typesof oil-bearing strata but it is especially applicable to formationscontaining highly viscous crude such as are found in Monagas, Venezuela,and in certain areas of the United States and Canada. It is alsoapplicable to the production of tar sands and shales which havesufficient permeability to permit steam injection or which have beenfractured to provide for steam injection. In some formations containinghighly viscous crudes, the injected steam not only causes oil to flowinto the well but also renders the crude readily pumpable whereas,

without substantial heating of the crude, it is not readily pumpable.

Expansion of the tubing string during steam injection is accommodated byslippage thru the packer. There will be a lesser amount of expansion ofthe casing and this expansion is effected upwardly. Accommodation ofcasing expansion is made in the bradenhead where slippage thru thepacking gland results.

Certain modifications of the invention will become apparent to thoseskilled in the art and the illustrative details disclosed are not to beconstrued as imposing unnecessary limitations on the invention.

I claim:

1. A process for producing oilfrom an oil-bearing stratum penetrated bya well having a casing extending to said stratum and a tubing stringinto said stratum from a well head at ground level which comprises thesteps of:

(1) providing a pump in pumping position in the lower end of said tubingstring slidably sealed therein;

(2) providing an enlarged section of tubing in said tubing string abovethe pumping position of said pump for housing said pump in retractedposition and providing a flow annulus between said pump and the wall ofsaid enlarged section;

(3) alternately injecting hot fluid into said stratum thru said tubingand said flow annulus with said pump in retracted position and pumpingliquid accumulating in said well with said pump sealed in pumpingposition, thereby alternately heating and causing oil to flow into saidwell and pumping the produced oil to ground level.

2, The process of claim 1 wherein said hot fluid is steam.

3. The process of claim 1 wherein said hot fluid is hot water.

4. The process of claim 1 wherein said hot fluid is hot gas.

5. A process for producing oil from an oil-bearing stratum penetrated bya well having a casing extending to said stratum and a tubing stringinto said stratum from a well head at ground level which comprises thesteps of:

(1) providing a pump in pumping position in the lower end of said tubingstring slidably sealed therein;

(2) providing an enlarged section of tubing in said tubing string abovethe pumping position of said pump for housing said pump in retractedposition and providing a flow annulus between said pump and the wall ofsaid enlarged section;

(3) injecting steam thru said tubing into said stratum with said pump inretracted position until a substantial amount of oil in said stratumaround said well is rendered less viscous, flows into, and accumulatesin said well;

(4) thereafter, lowering said pump into pumping position and pumping theaccumulated oil to ground level.

6. The process of claim 5 wherein steps (3) and (4) are alternatelyrepeated.

7. A process for injecting a fluid into a well thru a tubing stringtherein, having a sucker rod carrying pumping means removably sealed inthe lower end of the tubing string, without pulling the rod and pumpingmeans from the tubing, which comprises the steps of:

(1) providing an expanded section of tubing above said pumping means andnear the lower end of said tubing, having an internal diameter andlength substantially greater than the external diameter and length ofsaid pumping means, so that when said pumping means is pulled into saidsection a flow path around same within said tubing is formed;

(2) retracting said pumping means into said section of tubing so as toform said flow path; and

(3) injecting a fluid thru said tubing into said well while said pumpingmeans is in said expanded section.

8. The process of claim 7 wherein said fluid is a heating 9. The processof claim 7 wherein said fluid is steam.

10. Apparatus in an oil well having a casing and well head andpenetrating an oil-bearing stratum comprising in combination:

(a) a tubing string extending thru said well head into said stratum;

(b) a section of tubing in the tubing string of (a) of substantiallylarger internal diameter than the adjacent tubing and substantiallylonger than the pump means of (c), said section being near the bottomend of said tubing string;

(c) a pump means in the tubing string of (a) attached to the lower endof a sucker rod extending from the well head to the lower end of thetubing string, said pump means being alternately movable into pumpingposition sealed with the wall of said tubing string below said sectionand then into said section to provide a passageway around said pumpmeans and thru the lower end of said tubing for injecting fluid thrusaid tubing string and around said pump means into said stratum.

11. The apparatus of claim 10 wherein said casing extends substantiallyto said stratum and including a packer around said tubing stringadjacent said section closing off the annulus between said casing andsaid tubing string, said tubing string being slidably sealed with saidpacker to provide for expansion of said tubing string when hot fluid isinjected therethru.

12. The apparatus of claim 10 wherein said pump means comprises a rodpump removable with said rod.

13. The apparatus of claim 10 wherein said pump means comprises a tubingpump having a standing valve removable with the pump plunger attached tosaid rod.

References Cited by the Examiner UNITED STATES PATENTS 1,703,423 2/1929Herman 103-1 1,804,078 5/1931 Baden 1031 2,078,107 4/1937 Ten Brinkl66--62 3,126,961 3/1964 Craig et a1. 166-50 CHARLES E. OCONNELL,Primary Examiner.

S. J. NOVOSAD, Assistant Examiner.

7. A PROCESS FOR INJECTING A FLUID INTO A WELL THRU A TUBING STRINGTHEREIN, HAVING A SUCKER ROD CARRYING PUMPING MEANS REMOVABLY SEALED INTHE LOWER END OF THE TUBING STRING, WITHOUT PULLING THE ROD AND PUMPINGMEANS FROM THE TUBING, WHICH COMPRISES THE STEPS OF: (1) PROVIDING ANEXPANDED SECTION OF TUBING ABOVE SAID PUMPING MEANS AND NEAR THE LOWEREND OF SAID TUBING, HAVING AN INTERNAL DIAMETER AND LENGTH SUBSTANTIALLYGREATER THAN THE EXTERNAL DIAMETER AND LENGTH OF SAID PUMPING MEANS, SOTHAT WHEN SAID PUMPING MEANS IS PULLED INTO SAID SECTION A FLOW PATHAROUND SAME WITHIN SAID TUBING IS FORMED; (2) RETRACTING SAID PUMPINGMEANS INTO SAID SECTION OF TUBING SO AS TO FORM SAID FLOW PATH; AND (3)INJECTING A FLUID THRU SAID TUBING INTO SAID WELL WHILE SAID PUMPINGMEANS IS IN SAID EXPANDED SECTION.
 10. APPARATUS IN AN OIL WELL HAVING ACASING AND WELL HEAD AND PENETRATING AN OIL-BEARING STRATUM COMPRISINGIN COMBINATION: (A) A TUBING STRING EXTENDING THRU SAID WELL HEAD INTOSAID STRATUM; (B) A TUBING STRING EXTENDING THRU SAID WELL HEAD INTOSUBSTANTIALLY LARGER INTERNAL DIAMETER THAN THE ADJACENT TUBING ANDSUBSTANTIALLY LONGER THAN THE PUMP MEANS OF (C), SAID SECTION BEING NEARTHE BOTTOM END OF SAID TUBING STRING; (C) A PUMP MEANS IN THE TUBINGSTRING OF (A) ATTACHED TO THE LOWER END OF A SUCKER ROD EXTENDING FROMTHE WELL HEAD TO THE LOWER END OF THE TUBING STRING, SAID PUMP MEANSBEING ALTERNATELY MOVABLE INTO PUMPING POSITION SEALED WITH THE WALL OFSAID TUBING STRING BELOW SAID SECTION AND THEN INTO SAID SECTION TOPROVIDED A PASSAGEWAY AROUND SAID PUMP MEANS AND THRU THE LOWER END OFSAID TUBING FOR INJECTING FLUID THRU SAID TUBING STRING AND AROUND SAIDPUMP MEANS INTO SAID STRATUM.